This invention relates to the provision of electromagnetic interference shielding of an electronic system.
Modern electronic systems equipment, such as for telecommunications purposes, is often constructed as modular circuit card assemblies inserted into parallel guide slots of mechanical card cages, or shelf units, for engagement with a backplane mounted to the shelf unit at the inward ends of the guide slots. The outward edge of each circuit card of each circuit card assembly is fastened to a face plate assembly which has a latch for releasably retaining the circuit card assembly in the shelf unit. Although the circuit card assemblies are relatively closely packed, there are still gaps between adjacent face plate assemblies. These gaps allow electromagnetic interference radiation to leak therethrough. A need therefore exists to provide shielding against electromagnetic interference for such electronic systems equipment.
Each face plate assembly typically includes a conductive member, or bracket, which extends along the length of an edge of the circuit card. The bracket is commonly C-shaped with a pair of parallel arms flanking the circuit card. It is known to adhere a conductive gasket to the outwardly facing surface of one of the bracket arms, with the gasket extending sufficiently away from that arm so as to engage the other bracket arm of the circuit card assembly in the next adjacent slot in the shelf unit. However, it has been found that such gaskets tend to peel away from the bracket arm after a number of removals and insertions of a circuit card assembly from a shelf unit. Therefore, there exists a need to provide a shielding gasket which is not subject to peeling away from the bracket when the circuit card assembly is removed or inserted.